The present invention relates generally to the area of computer-aided design and computer-aided manufacturing (CAD/CAM) software, and more specifically to methods for enabling the transfer of three-dimensional data between CAD/CAM software applications.
Object Linking and Embedding (OLE) Overview
Within the office environment, one method that has been developed to enable "cutting" and "pasting" of data between software applications is "object linking and embedding (OLE). OLE defines standardized interfaces and functions enabling users to transfer "objects" between software applications. The following section is an abbreviated overview of some of the concepts used in OLE version 2.0, from Microsoft Corporation of Belleview, Wash., and defines some of the terms that will be used in the disclosure. Further information and details about OLE may be obtained from "Inside OLE 2" by Kraig Brockschmidt, 1994, Microsoft Press, hereby incorporated by reference.
An example of cutting and pasting data between software applications is illustrated in FIG. 1. FIG. 1 illustrates a two-dimensional object 1 created in a first software application being transferred into a second software application. The first and second software applications (not shown) are commonly specialized software applications such as spread-sheets, word processors, or graphics programs. Once two-dimensional object 1 has been transferred, the second software application can manipulate its own data, two-dimensional object 2, so that two-dimensional object 2 interacts with two-dimensional object 1. The resulting document is then output to the user.
OLE provides a set of "interfaces", or groups of functions, which when combined provide the mechanics enabling the user to transfer data between programs. FIG. 2 illustrates the convention for representing an OLE interface 10, for an object 11 and a "consumer" 12 of the object. Object 11 is said to have an "interface implementation", including interfaces 13 and 14, that are analogous to an object oriented programming "class." Interfaces 13 and 14 include member functions 15 and 16, respectively, that are analagous to object oriented programming class "instances".
Consumer 12 receives data from object 11 by calling functions of interface 13 and/or interface 14. In some cases the consumer may only be aware of one of several interfaces available in an object. In response to the function calls, object 10 may return specific data about itself to the consumer 12. Object 10, however maintains exclusive control of its own data 17. As further illustrated in FIG. 2, IUnknown is an interface available to all object, that when queried for specific interfaces, returns pointers to the requested interface. For example, assuming consumer 12 knows which functions are available in interface 13, consumer 12 can ask and receive a pointer to interface 14. Then, once consumer 12 receives a pointer to interface 14, consumer 12 can call member functions 16.
The functions provided in the currently available OLE standardize the transfer of placement and size information, of objects between software applications. Two type of "transferring" objects from a first software application to a second software application include "linking" and "embedding".
"Linking" an object that is created in a first software application to a second software application is when the object maintains its existence separate from the second software application, although the second software application can "use" and reference the object. Linking also allows the user to modify and edit the object with the first software application without having to invoke the second software application.
"Embedding" a first data object into a second software application is when the object is actually integrated with the data stored and used by the second software application. Embedding allows the user to modify and edit the object only after first invoking the second software application.
"Linking" an object is commonly preferred when the linked object includes a large quantity of data. One drawback to linking however, includes maintaining and remembering the particular path or directory of the linked object in the computer memory. "Embedding" an object is commonly preferred when the positioning and relationship of the embedded object to other data within the second software application is important to maintain. One drawback to embedding however, includes that the embedded object cannot be edited or modified by the user without invoking the second software application.
Two other commonly used OLE terms are "servers" and "containers". As illustrated in FIG. 2, the data 17 actually is only a portion of the object 10. The functions 15 and 16 serve to manipulate data 17 and to convey this data to the consumer 12. Because object 10 "serves" and manages the data, it is often called a "server". A "container" is defined as the user of the information contained within the server. In FIG. 2, the container is consumer 12. In a macroscopic scale, in the example in FIG. 1, the server is the first software application which manages object 1, and the container is the second software application. A container may access multiple servers, one for each object within the container's "environment" and further, containers and servers may be nested.
The term "In Place Activation" is another important term in OLE. "In Place" activation enables a first software application to be active within a second software application. As illustrated in FIG. 1, an object 1 created in a spreadsheet application is inserted into a document 2 created by a word processing application. Without In Place activation capability, once object 1 is inserted into document 2, if the user wishes to revise the entries in object 1, normally the user would have to quit the word processing application, enter the spreadsheet application, revise object 1, reinvoke the word processing program and then transfer the revised object 1. This indirect manner of editing transferred object occurs because the software application receiving the object only recognizes the object as a two-dimensional black box. With In Place activation, the user can directly invoke the spread sheet application from within the word processing application. OLE provides the interface capability for the two software applications so they can communicate with each other. As a result, the user can revise object 1 using the spreadsheet application without quitting the word processor application.
OLE version 2.0 is currently available with Microsoft Corporation's Windows.TM. operating system version 3.1. Currently many office environment software applications such as Microsoft Corporation's Excel and Word support OLE standards and interfaces. As was illustrated in FIG. 1, object 1, created in a first software application such as a spread sheet, is transferred into a second software application such as a word processor. Among other variables passed between the software applications, the second software application needs to know the two-dimensional size of the object 1 so that it can make room for it in the document. The second software application obtains the two-dimensional size of first data object 1 by calling and relying on OLE functions. Based upon the two-dimensional size, the second software application can modify its own data, object 2, to "wrap around" object 1.
OLE is not limited to two-dimensional objects and is also used to incorporate and transfer audio and video data between software applications. Current OLE functions work well with office environment data objects, i.e., two-dimensional objects that are defined by a two-dimensional bounding boxes. OLE functions however, only allow the user to perform rudimentary two-dimensional functions on the boxes such as resizing, locating, and rotating.
CAD/CAM Marker Overview
Application software specifically designed for architectural and engineering purposes are commonly labeled Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) software. Some of the standard features of the CAD/CAM applications is the ability to create and manipulate three-dimensional objects and to position three-dimensional objects relative to other three-dimensional objects.
As illustrated in FIG. 3, a three-dimensional object in a CAD/CAM environment is typically represented as a two-dimensional image to the user in the form of a print-out or display. Examples of commonly displayed views of a three-dimensional object are a top, right-side, front, and isometric views. FIG. 3 illustrates that a top view, a right-side view, and a front view of three-dimensional object 20 are derived from orthogonal projections onto a top two-dimensional plane 21, a right-side two-dimensional viewing plane 22, and a front two-dimensional viewing plane 23, respectively. FIG. 3, also illustrates that an isometric view of three-dimensional object 20 is derived from projections onto isometric viewing plane 24.
In the past, CAD/CAM software applications were tightly coupled to specialized computer hardware because of the heavy computational and display demands of the software. Because of this specialization, these CAD/CAM workstations were complete, self-contained working environments. Once the user one vendor's workstations, there would be little possibility to use another vendor's workstations due to cost considerations. Because the user tended to stay with a particular vendor in the past, there was little need to transfer three-dimensional objects created in a first CAD/CAM application to a second CAD/CAM application.
With the increase in processing capabilities of personal computers, personal computers are now replacing the traditional workstations of the design engineer. This shift in the CAD/CAM computing environment has lessened the ties of the user to a particular vendor and now allows the user to choose the CAD/CAM application that best suits the problem or the user's preferences. In addition, with the increase in computing platforms, more than one engine can now work on the same problem simultaneously.
Currently, CAD/CAM packages from different vendors rely upon proprietary data formats and do not allow the user to transfer objects created in one software application to another vendor's software application. Thus although computer hardware has become more advanced, the CAD/CAM software has not. What is needed are software functions and tools that enable the user to transfer data objects created by a first CAD/CAM software application into a second CAD/CAM software application.
Currently, if the user attempted to use the present two-dimensional functions of OLE and apply them in the area of CAD/CAM applications, the shape of a three-dimensional object would fail to be transferred. FIG. 4 illustrates a front view 30 of a first three-dimensional object created by a first software application and an isometric view 31 of a second three-dimensional object created by a second software application. Consistent with the OLE standard, front view 30 is defined by a bounding box 32 having dimensions 33 and 34. When front view 30 is transferred to the second software application, the second software application merely sees two-dimensional bounding box 32 and has no understanding of how to integrate the two objects in three-dimensional space. Because office environment concepts of data objects are only two-dimensional objects that are defined by two-dimensional bounding boxes, OLE is ill suited for use in the field of CAD/CAM applications. Further, even if it were somehow possible to transfer the two-dimensional shape of a first three-dimensional object into a second software application, OLE does not provide a mechanism for transferring depth information of an object.
What is needed is a standardized method for allowing the user to transfer three-dimensional data between software applications.